Psych Ch. 4 Terms-- Sensation And Vision

Front 1

sensation

Back 1

processes by which our sense organs receive information from the environment

Front 2

perception

Back 2

processes by which we select, organize, and interpret sensations

Front 3

What are the three types of processing?

Back 3

Transduction, Coding, and Sensory Reduction

Front 4

Transduction

Back 4

converts sensory stimuli into neural impulses that can be translated by brain

Front 5

Coding

Back 5

converts sensory stimuli into specific sensations/ puts them into a specific category

Front 6

Sensory Reduction

Back 6

filters and analyzes incoming sensations before sending a neural impulse to the brain

Front 7

Sensory Adaptation

Back 7

reduction/disappearance of sensory responsiveness when stimulus is unchanging or repitious; prevents us from having to respond continuously to unimportant information

Front 8

Distal stimulus

Back 8

the real object (or person) in the world outside of us; usually at some distance from the perceiver

Front 9

Proximal stimulus

Back 9

the pattern of light that is refelected off of the person's or object's outer surface, collected by our eyes, and cast as an image on the retina; usually "nearby" the perceiver; doesn't have to be light... it can be whatever is sensed (ex. scent molecules)

Front 10

Psychophysics

Back 10

the study or the relationship between physical stimulation and subjective experiences that result

Front 11

Absolute Threshold

Back 11

the smallest amount of stimulation that can be detected--

Front 12

Just Noticeable Difference (JND)

Back 12

the smallest amount of change in a stimulus that can be detected--how much more is needed before the change is noticed; can be predicted by Weber's law; proportional to original stimulus

Front 13

Weber's Law
-What is it and what does it tell us?

Back 13

Tells us that the size of the JND (just noticeable difference) is a constant fraction (proportional) of the original stimulus it's being compared to; it tells us that we are sensitive to percentage changes rather than absolute changes; allows us to compare sensitivities of different senses/modalities; change in intensity (amount added to original stimulus in order to produce a jnd) divided by original standard stimulus intensity equals the constant fraction

Front 14

Signal Detection Theory
What is it? How does it work?
What are "hits" and "misses"?

Back 14

psychophysical theory that divides detection of a sensory signal into a sensory process and a decision process;provides useful way to think about how people make decisions and attempts to minimize inevitable errors; four possible outcomes--> "hits" are true/correct positive and true/correct negatives or rejections; "misses" are false positives or alarms and false negatives

Front 15

Pattern Theory

Back 15

Explanation for sensory quality that says input is identified by the pattern of activation-- which neurons are firing more and which are firing less at any given moment (what neurons are being activated in response to a stimulus)-- all neurons for senses fire in response to stimulus but the pattern of how they activate/fire and the amount/intensity they fire determines what is sensed/coded

Front 16

light

Back 16

form of electromagnetic radiation that travels as a wave-- waves may have different amplitudes, wavelengths, and frequencies; reflected light is what we see (vision)

Front 17

wavelength

Back 17

what we perceive as hue or color; distance/time between crests

Front 18

amplitude

Back 18

what we perceive as brightness; the amount of pressure by each air particle on the next; height of wave

Front 19

saturation

Back 19

what we perceive as purity of color; more pure=brighter=more saturated; less pure=more dull=less saturated (more gray, black or white mixed in)

Front 20

what is the visible spectrum of light for humans?

Back 20

light with wavelength between 400 nm (violet) and 700 nm (red)

Front 21

Cornea

Back 21

the eye's transparent outer coating that helps focus incoming light; fixed in shape but begins process of bending light rays so they will end up properly focused

Front 22

Iris

Back 22

eye structure that controls the amount of light entering the eyeball and reaching retina ; smooth, colored, circular muscle that surrounds pupillary opening and contracts or dilates under reflex control as the amount of illumination changes

Front 23

Pupil

Back 23

opening in the center of the iris (controls it); size of this determines how much light enters the eye; hole in iris through which light passes

Front 24

Lens

Back 24

portion of the eye that can bend light rays and focus an image onto the retina; can adjust shape by a band of muscle that surrounds it; further focuses light on retina

Front 25

Retina

Back 25

layer of tissue lining the back of the eyeball that produces retinal image of what is being seen; where visual information is perceived and sent to the brain

Front 26

Fovea

Back 26

a small, roughly circular region at the center of the retina where cones are plentiful and vision is best

Front 27

Optic Nerve

Back 27

bundle of fibers made up of ganglion cells that leaves the eyeball and carries information to the lateral geniculate nucleus and then the cortex of the brain

Front 28

Rods

Back 28

type of receptor cell in the retina; very sensitive but less acute and are for dim light / night vision; absent in fovea; more in periphery; low light intensity; 120 million; contain only one photopigment (shades of gray)

Front 29

Cones

Back 29

type of receptor cell in the retina; specialized for very acute detail, feature 3 different photopigments whose molecules absorb light energy causing a neuron to fire; plentiful in the fovea; less in periphery; day vision, high illumination and detail, perceive color; 6 million cells

Front 30

eye

Back 30

housing neural tissue that channels light toward the retina

Front 31

Trichromatic Theory for Color Vision

Back 31

Researchers found that by mixing only three primary colored lights (blue, red, and green) they could create all possible colors--> led to the idea that we have receptors for 3 colors of red, green, and blue, which correspond to the 3 types of cones (true and based on sensitivity to wavelength)-- the combination of the three in various patterns leads to color we see; Red=long wavelength; Green= medium wavelength; Blue= short wavelength

Front 32

rhodopsin

Back 32

the single photopigment in rods of the eye

Front 33

Opponent Process Theory for Color Vision

Back 33

Says that visual system also analyzes information in terms of three pairs of "opponent" colors, which are red & green, black & white, and blue & yellow; this process adds to trichromatic theory and says that different colors can be fired for and combine to "see" another color -- color is perceived based on a balance; organizes the output of the cones; excitation of one color inhibits the other opponent-- balance

Front 34

(negative) afterimage

Back 34

shows the complimentary hue of a stimulus-- ex. stare at green spot for a while and then look at a white wall-- see a red spot that isn't actually there

Front 35

photopigment

Back 35

a chemical that is sensitive to light and allows the transduction of light energy into a neural signal; when light enters the receptor, the energy changes into chemical form of this in order to set off a chain of events to lead to an electrical signal

Front 36

complementary colors

Back 36

two colors that produce gray when they are additively mixed together in the right proportions; idea that colors are "paired" and have "opposites" that cancel them out-- applies to any color in chromatic region of visual field

Front 37

Young-Helmholtz Theory

Back 37

View that suggests color vision is based on three basic elements -- stimulation by red light activates long-preferring receptors and only weakly activates the other two receptors; stimulation by blue light strongly activates the short-preferring receptors and only weakly activates the other two; stimulation by green light strongly activates the medium-preferring receptors and only weakly activates the other two

Front 38

feature detectors

Back 38

Cells that detect certain elements within the visual pattern; fire in response to a line or edge of a particular orientation and other basic elements

Front 39

receptive field

Back 39

region with certain shape and size within the visual field that cell responds to; cells act as "detectors" and respond when preferred target is in view (curve, angle, line, etc.)-- identifies type of detector to see image